Experimental study of instantaneous sound intensities in rectangular enclosures

Abstract

Instantaneous and time-averaged intensities are relevant field quantities in architectural acoustics investigations. Modeling of intensity flows in coupled volumes and the effect of absorptive material on its trajectory in reverberation chambers have been studied recently. This work focuses on vortical energy flows with a derivation of instantaneous intensity in enclosed spaces and an experimental effort for investigating the changes over time in all field quantities of interest—instantaneous intensity, pressure, and velocity simultaneously. In this study, the scale modeling technique is applied to investigate instantaneous intensity flows experimentally measured using pressure-3D velocity sensors in a rectangular room. Experimental results suggest the presence of vortical intensity modes at specific frequencies correlated to the room dimensions. The resulting simulation of intensity vortices has potential applications in the acoustical design and analysis of complex room geometries where sound energy flows play a major role in the acoustics of the space such as that of coupled-volume spaces and small rooms for critical listening.